High power microwave generator

Abstract

Conversion of electron beam energy into high power microwave energy is efted within the cavity of a Klystron device to which the electron beam is accelerated from a continuous supply source through an ion focussing channel. Ion focussing is achieved by establishment of a preionized background plasma within the channel to modulate the current of the electron beam in response to wake field effects and cause bunching of the electron beam during propagation to the Klystron device.

We claim: 
     
       1. In combination with a Klystron device having a cavity within which microwave energy is generated in response to propagation of a relativistic high-current electron beam, a continuous source of electrons, channel means to which said electron beam is continuously supplied from the source for propagation into the cavity of the Klystron device and means establishing a preionized background plasma within said channel means for current modulation of the electron beam and bunching thereof prior to entry into the cavity of the Klystron device. 
     
     
       2. The combination of claim 1 wherein kinetic energy of the electrons in the electron beam is converted into the microwave energy within the cavity substantially equal in frequency to that of the background plasma. 
     
     
       3. In a microwave generator having a cavity within which kinetic energy of electrons from a source is converted into microwave energy at a predetermined frequency, accelerator means connected to said source for continuous supply of an intense beam of the electrons, channel means connected to said accelerator means for directing said beam of the electrons to the cavity and ion focussing means for current modulation of the said beam of the electrons during propagation through the channel means as a result of wake field effects. 
     
     
       4. The combination of claim 3 including a drift tube extending from the channel means into the cavity through which bunching of the beam occurs because of the wake field effects. 
     
     
       5. The combination of claim 4 wherein said wake field effects include electrostatic establishment of an electric field within the channel means having axial and radial components. 
     
     
       6. The combination of claim 5 wherein said axial component of the electric field produces said current modulation of the electron beam while the radial component produces oscillation of plasma electrons approximately at said predetermined frequency of the microwave energy. 
     
     
       7. The combination of claim 3 wherein said wake field effects include electrostatic establishment of an electric field within the channel means having axial and radial components. 
     
     
       8. The combination of claim 7 wherein said axial component of the electric field produces said current modulation of the electron beam while the radial component produces oscillation of plasma electrons approximately at said predetermined frequency of the microwave energy.